SE2250604A1 - Demolition robot and method for feeding hydraulic power to a hydraulically driven tool at a demolition robot - Google Patents

Abstract

The invention relates to a demolition robot exhibiting at least one hydraulically active function, which demolition robot (1) includes; an incoming supply line (P) for hydraulic flow, an outgoing return line (T) for hydraulic flow, and an outgoing load sensing line (LS), In order to meet the power needs of the demolition robot, the sensing device (30) for sensing a pressure in connection with the hydraulically active function or in connection with the load sensing line (LS), a control device (40) comprising a pump (13') for generating a hydraulic flow and a drive motor connected to said pump ( 15') with assigned motor drive unit (52') which allows speed regulation of the drive motor, a control unit (50) which is arranged to receive a signal from the sensor device (30) and to control the speed of the drive motor (15') included in the control device (40) to causing the pump (13') to produce a predetermined pressure on the load sensing line (LS).

Description

Demolition robot and method for feeding hydraulic power to a hydraulically driven tool in a demolition robot Technical field The present invention relates to a remote-controlled demolition robot that is fed with hydraulic power via a load-sensing system, a so-called LS system, from a power supply unit included in the demolition robot, and a method for supplying hydraulic power to a tool carried by the demolition robot.

Background With remote-controlled demolition robots that use hydraulically driven tools, problems can occur when a hydraulic tool's hydraulic pressure and hydraulic flow requirement differs significantly from the hydraulic pressure and flow requirement of other actuators and actuators, such as a hydraulic cylinder to operate an arm included in the demolition robot, which at its free end carries said tool. For example, an operator of the demolition robot may experience that the maneuverable arm does not obey the operator's control commands to perform movement of the arm while a power-demanding tool is performing work.

In displacement-type hydraulic systems, a liquid is forced to flow through the action of a pump, whereby the liquid is pressurized corresponding to the pressure exerted by the load. Said load can consist of a load moment from a hydraulic motor or the load force from a hydraulic cylinder. The power transmitted in a hydraulic system is defined as the pressure of the liquid (N/mz) multiplied by the volume flow (mf/second). Without control, all hydraulic flow in a system would follow the law of least resistance, ie. primarily flow to the other consumer or the load that offers the least resistance of pressure (back pressure).

In order for hydraulic flow not to flow uncontrolled, but de facto delivered to the other consumer of the demolition robot who currently has the greatest need for power, advanced load sensing systems "Load Sensing", so-called LS system for supplying hydraulic power. LS systems make it possible to control and regulate the hydraulic flow to the same loads as the demolition robot, i.e. to the range of different functions of the demolition robot that consume hydraulic power, In the case of LS systems in previously known demolition robots, a pump with a built-in flow regulator is used. The controllable pump forms part of a control device whereby a hydraulic measurement signal at a consumer informs the pump to what degree it should angle out in order to give the current consumer the desired flow The pump's output flow is automatically adjusted to the sum of the current flow demand of all consumers if several consumers are activated P :\Stockho|m\mfh\Desktop\Desktop 171207\New Fo|der\Brokk\P41801041SEOO131403738 EOO\P140373S EO1\220519 besk o patent claim divided application.docx at the same time. When all directional valves are in neutral position, the pump is maximally angled in and thus emits "0 flow". LS systems are the most common type of system for work hydraulics in mobile machine equipment, as both pump pressure and flow can be automatically adapted to current needs in each operating situation.

It should be mentioned that LS systems generate an "unnecessary" power loss that averages around 10% of input hydraulic power. Through appropriate system settings, however, this power loss can be minimized, but at the cost of the system's response times (response times) increasing and also the dependence of the pump flow on the viscosity of the hydraulic fluid.

Fig. 1 shows an electrically driven demolition robot 1 of the type that is intended to be connected via a cable 2 to an outlet in an electrical network, for example a 400 V AC three-phase network. The demolition robot 1 has a maneuverable arm 3 at the free end of which a consumer L1 in the form of a tool such as a hydraulically operated hammer is supported. In order to perform movements, the arm is affected by one or several hydraulic cylinders which, as a consumer, are denoted by L2 in the figure. An operator 6 walks next to the demolition robot 1 and remotely controls it via radio link by means of a portable control box 7 equipped with the necessary control levers 8 and controls. At its free end, the arm 3 carries a tool in the form of a hydraulically driven hammer which, viewed as a consumer, is denoted by the L1 figure. In comparison to a hydraulic cylinder, a hydraulically driven hammer, which is driven by a hydraulic motor, is to be considered a particularly power-demanding tool whose volume flow requirement is very high.

Hydraulic hammers are widely used in a demolition robot. Due to the hydraulic hammer's relatively large power requirement in relation to, for example, a hydraulic cylinder for a maneuverable arm 2, the operator 6 may experience that the arm 3 does not obey the operator's control commands to perform movement of the arm at the same time as the tool performs work, while the amount of pressurized hydraulic flow is simply not enough.

As mentioned above, the basic principle of a mobile LS system is that it is load-sensing and pressure-compensated, which means that a certain lever position on the operator's 6 control box7 gives rise to a control signal that represents a requested flow to a consumer, i.e. to a load or hydraulic function regardless of the load on this and regardless of the outflow to and the load on other consumers.

In the following, the term "hydraulic actuated function" refers to a function or consumer that has been activated by an operator for operation by means of a control lever or similar controls on a control box.

When the lever position is set, a consumer, for example a hydraulic cylinder, requests a specific flow from a controllable pump with variable displacement volume included in the system. Said requested flow needs are controlled and controlled by a sensing device through pressure measurement and through the influence of hydraulic measurement signal, i.e. basically a pressure signal via a hose that is connected between a function valve and an LS connection included in the pump. The controllable P:\Stockholm\mfh\Skrivbord\Skrivbord 171207\New Folder\Brokk\P41801041SEOO131403738 EOO\P140373S EO1\220519 besk o patent claim divided application.docx pump forms part of a control device that senses and via the pressure signal tells the pump to what degree it should angle out to give the current consumer the desired flow. As long as the pressure drop across the directional valve and the consumer is constant and does not significantly deviate from a predetermined pressure level, the system perceives it as the consumer receiving the requested flow.

Fig. 2 shows the principle in more detail for an LS system in a known demolition robot. Schematically, the system comprises a group generally of 20 labeled consumers illustrated as first and second consumers L1, L2 and of which the first consumer L1 can be constituted by hydraulic motor to drive a hydraulic hammer and the other consumer L2 of a hydraulic cylinder for operating the demolition robot's armLS system further comprises a pump 13, a tank 14 for hydraulic fluid and an electric motor 15 which, according to known technology, consists of a three-phase asynchronous motor (AC motor), i.e. a motor with constant speed at specified rated power. The rotation speed of this type of motor is normally in the range of 1800 to 3600 rpm depending on the type of machine.

The LS system comprises three lines; a supply line P, a return line T and single load sensor line LS. Via the supply line P, hydraulic fluid is fed from tank 14 via pump 13 to the first and second consumers L1, L2. Via the return line T, hydraulic fluid from said first and second consumers L1, L2 is returned to tank 14. The load sensor line LS forms part of a sensor device designated 30 with which, via a valve 12, a hydraulic measurement signal is retrieved from a hydraulically activated function and which can, for example, indicate a maximum pressure at a measuring point in between a directional valve included in the system FV1, FV2 and consumer L1, L2. The hydraulic measuring signal from the valve 12 is directly connected to the LS input of the pump 13 and which unit forms part of a generally 40 designated control device. The control device 40 is hydraulically connected to the load sensing line LS as well as to at least one of the supply line P and the return line T. With the help of the hydraulic measurement signal, the operating state of the pump 13 is affected so that a predetermined or requested flow is maintained based on the prevailing pressure of the activated hydraulic function or the consumer.

For this purpose, the pump 13 comprises a controllable pump with variable displacement, which means that the volume stream of flow emitted from the pump can be regulated by varying the angular position of the pump. The speed of the AC drive motor 15 of the pump 13 is, however, constant. Based on the prevailing hydraulic pressure of the consumer, the variable pump 13 is thus controlled in such a way that it delivers the flow that is requested in accordance with the lever position 8 set by the operator 6 on the portable control box The LS system has a number of advantages, not least that the flow from pump 13 to consumers L1, L2 is automatically adjusted to the existing need and that the pump can be controlled down (angled P:\Stockholm\mfh\Skrivbord\Skrivbord 171207\New Folder\Brokk\P41801041SEOO131403738 EOO \P140373S EO1\220519 besk o patent claims divided application.docxin) so that it emits "O flow" to avoid losses at idle or at very low power demand.

However, this only applies as long as the sum of the hydraulic flow requested by means of the levers 8 on the control box 7 to the consumers L1, L2 is less than or equal to the maximum hydraulic flow that the pump 13 can deliver.

When the total, requested hydraulic flow to the two first and second consumers L1, L2 exceeds the maximum hydraulic flow that can be delivered from the pump 13, the flow is directed first and foremost to the consumer with the lowest load and thus the highest registered pressure. The consumer with the highest load (lower pressure) gets, in the worst case, no hydraulic flow at all and can freeze. This phenomenon, that one or more consumers and thus functions of components surprisingly become without flow is usually called "puncture".

One solution to the problem has so far been to oversize the demolition robot's 1 pump 13 and, as a consequence, also the associated drive motor 15 so that the flow from the pump is always sufficient, regardless of which maneuvers an operator 6 indicates on the control box 7 and/or which consumers L1, L2 are activated for joint or combinative operation. Such overdimensioning not only has the disadvantage that the hydraulic system becomes more expensive and requires more energy, but also that the system as a whole becomes more space-consuming and heavier, which is not desirable, especially when it comes to a mobile system for a demolition robot.

Summary A first aim of the present invention is thus to create a demolition robot which is fed with hydraulic power via a load-sensing system, an LS system from a power supply unit included in the demolition robot which solves this problem and which makes it possible to create a small compact energy-efficient system without the risk of puncture in an improved dynamic or feedback manner can meet the demolition robot's power needs.

A second purpose of the invention is to provide a method for supplying hydraulic power to one or more loads carried by the demolition robot, such as a hydraulically driven tool.

This first object of the invention is solved by a demolition robot that exhibits features and characteristics stated in the patent claim.

Brief description of the drawings P:\Stockholm\mfh\Skrivbord\Skrivbord 171207\New Folder\Brokk\P41801041SEOOP140373S EOO\P140373S EO1\220519 besk o patent claim divided application.docx In the following, a demolition robot according to the invention is described which is fed with hydraulic power via a load sensor system, a so-called LS system, from a power supply unit included in the demolition robot closer, whereby; Fig. 1 shows a side view of a remote-controlled demolition robot according to the invention which is fed with hydraulic power via a load-sensing system, a so-called LS system, from a power supply unit included in the demolition robot, Fig. 2 schematically shows a block diagram of a load-sensing system, a so-called LS system, which is part of a power supply unit of a known demolition robot, Fig. 3 schematically shows a block diagram of a load-sensing system, a so-called LS system, according to the invention which is part of a power supply unit of a demolition robot, Fig. 4 shows a block diagram for speed control of an electronically controllable permanent magnet motor (PM motor) especially an inverter-fed permanent magnet AC motor (PMAC) which can be part of the present invention, and Fig. 5 schematically shows an illustration in graphic form of the pump capacity at varying speed with a permanent magnet motor (PM motor) of the high speed type which allows speed regulation in accordance with the invention.

Detailed description Fig. 1 shows an electrically powered demolition and demolition robot 1, hereinafter referred to as demolition robot intended to be connected via a cable 2 to an outlet in an electrical network, for example with a network voltage of 400 VAC. The demolition robot 1 has a maneuverable arm 3 at the free end of which a tool in the form of a hydraulically driven hammer is supported. Examples of other common tools in the form of concrete shears and a bucket are also shown in the figure.

To perform movements, the arm is actuated by hydraulic cylinders. The hydraulic hammer and the hydraulic cylinder constitute functions that form a first consumer L1 and a second consumer L2, respectively. An operator 6 walks next to the demolition robot 1 and remotely controls it via radio link by means of a portable control box 7 equipped with the necessary control levers 8 and controls. The operator 6 can thus always be at a reassuring safety distance from the demolition robot's work area.

The demolition robot 1 generally comprises a carriage 10 with an upper part 11a and a lower part 11b. The upper part 11a is rotatably mounted on the lower part 11b for pivoting in a horizontal plane about a vertical axis. The demolition robot 1 comprises a mobile hydraulic system with a hydraulic drive device which supplies said first and second consumers L1, L2 with hydraulic flow. The hydraulic drive device of the mobile hydraulic system comprises a hydraulic pump 13' which is driven by an electric motor 15' with adjustable speed.

P:\Stockholm\mfh\Skrivbord\Skrivbord 171207\New Folder\Brokk\P41801041SEOOP140373S EOO\P140373S EO1\220519 besk o patent claims divided application.docxThis electric motor 15' is advantageously of the permanently magnetized type with highly adjustable working area.

According to the principles of the invention, the expression drive motor with highly adjustable working range means that the motor can at least operate at a large speed range and speed that is in any case twice or more than the normal drive speed for the type of conventional (AC motor) demolition robots have been equipped with. A suitable PM motor should at least be able to operate a three-phase asynchronous motor in the rpm range known so far from 0 rpm up to about 2000-3000 rpm or more.

Swinging of the upper part 11a takes place through the action of a hydraulic motor not shown in the figure. The carriage's lower part 11b is provided with a propulsion device comprising caterpillar tracks 16. The caterpillar tracks 16 are driven by hydraulic motors 17. 18 denotes a support leg.

The arm 3 is provided at its free end with a tool holder 19 in which different types of tools or implements can be releasably attached and connected for hydraulic operation. The robot's arm3 and other functional units that consume hydraulic flow can be switched on and controlled through the influence of a hydraulic valve block (monoblock) which is housed in the demolition robot 1. A valve block comprises a number of different directional valves of which the figure shows a first directional valve FV1 and a second directional valve FV2 for regulating hydraulic flow to said first and second consumers L1, LDemolition robot 1's instantaneous power requirement can vary significantly depending on which hydraulically driven work component included in the demolition robot, such as a hydraulic cylinder or a hydraulic motor, which must be supplied with the required input power (liquid pressure and flow).

Fig. 3 shows a schematic of an LS system that is part of a power supply system according to the invention. L1 comprises a first consumer and L2 a second consumer. The first consumer L1 can be made up of a hydraulic motor to drive the hydraulic hammer and the second consumer L2 of a hydraulic cylinder for operating the demolition robot's 1 arm 3. In a known manner, the LS system further comprises a pump 13' preferably of piston type which is well suited for speed changes, tank 14 for hydraulic fluid an electric motor 15' with variable speed.

The LS system comprises three lines; a supply line P, a return line T and single load sensor line LS. Via the feed line P, hydraulic fluid is fed from tank 14 via pump 13' to consumers L1, L2. Via the return line T, hydraulic fluid is returned from consumers L1, L2 to tank14. PT denotes a pressure sensor which is connected to the function valve's LS output and which pressure sensor can generate an electronic measurement signal 31' regarding the pressure.

This electronic measurement signal 31' is retrieved via the load sensor line LS and a valve 12 and can indicate a highest occurring pressure in a hydraulically activated function, i.e. from a measuring point in between a directional valve included in the system FV1, FV2 and consumer L1, LP:\Stockho|m\mfh\Skrivbord\Skrivbord 171207\New Fo|der\Brokk\P41801041SEOO131403738 EOO\P140373S EO1\220519 besk o patent claims divided application .docx 20 denotes a group of consumers illustrated as a first and second consumers L1, L2 and of which the first consumer L1 can be made up of a hydraulic motor for driving a hydraulic hammer and the second consumer L2 of a hydraulic cylinder for operating the demolition robot's arm The drive motor 15 can in one embodiment include a conventional AC induction motor where the speed is controlled by a frequency inverter or permanent magnet motors (EC or PM motors).

In another embodiment, the motor may comprise a DC motor whose rotational speed is controlled by current regulation and suitable feedback, whereby part of the output signal is coupled to the system's input signal.

In an alternative embodiment, the electric motor 15' or the power source can comprise a (PM motor) specially permanently magnetized AC motor, so-called PMAC. A PM motor must be driven by an electronically electronically controllable permanent magnet motor, an inverter feed inverter that takes line current, rectifies it and generates a new current with a frequency adapted to the operating conditions encountered.

For the purpose of clarification, the drawing figures have reference designations for such parts that have been added or differ from the known technology shown in Fig. 2 indicated with prime signs.

The rotation speed of this type of PM motor is not only controllable, but is significantly above the speed of the three-phase asynchronous motor (AC motor) with which hitherto known demolition robots 1 have been equipped. The load sensing line LS consequently forms part of a sensing device denoted by 30 with which via a valve 12 and pressure sensor PT, said electronic measurement signal 31' can be retrieved from a hydraulically activated function. In contrast to the known technology previously described with reference to Fig. 2, the hydraulic measurement signal according to the present invention is not analog hydraulic, i.e. immediately connected to the LS input of a pump 13 with variable displacement volume. Instead, according to the present invention, a sensor device 30 is formed with a pressure sensor PT which can generate an electronic measurement signal 31' which can be addressed to an electronic control unit denoted by 50', with which also the control levers 8 of the control box 7 can communicate. The control unit 50' can suitably be programmable and CPU-based.

The control unit 50' contains a computer program ie. software that, based on the electronic measurement signal 31' and the lever position 7 set by the operator 6 on the control box 7, via a control signal 51' to a drive unit included in the PM motor can control and regulate the speed of the motor 15' so that the pump 13' can deliver the power in the form of flow and pressure of the hydraulic fluid requested by the hydraulically activated function or consumer L1 or L2.

P:\StockhoIm\mfh\Skrivbord\Skrivbord 171207\New FoIder\Brokk\P41801041SEOOP140373S EOO\P140373S EO1\220519 besk o patent claims divided application.docxAccording to the invention, the electronically controlled PM motor 15' with adjustable speed together with the pump 13' forms part of a control device generally denoted by 40. The electronically controlled PM motor 15' can thus automatically adapt its speed based on the control lever output 8 and thus to the current flow and pressure needs of consumers LV1, LV2. Because, in accordance with the invention, the flow delivered by the pump 13' is controlled by speed regulation of the PM motor 15', in contrast to the known technology described above, where the speed of the pump (electric motor) is constant and the flow delivered by the pump is controlled by means of a pump with a variable displacement volume in which the pump's working vanes or vanes angled in/out to give the current consumer the desired flow, with the present invention there is no need for a pump with variable displacement, but a relatively cheap compact constant pump with fixed displacement can be advantageously used.

Fig. 5 illustrates in more detail in the form of a graph produced in a diagram how the pump capacity and flow Q can be varied by speed control of a PM motor 15' of high speed type according to the invention.

Thanks to the PM motor's high speed range, for example between 0 and 40,000 rpm, in which it maintains a high degree of efficiency even in the lower speed registers, optimal performance and a relatively low noise level can be achieved. In particular, when the demolition robot 1 works with simpler tools that allow lower power output (reduced engine speed) in contrast to demolition robots of a known type with a conventional three-phase asynchronous motor (AC motor) whose noise level is essentially constant during an entire work cycle after start independent of the finishing tool.

Mechanical power in Watts (W) of an electric motor is calculated according to the formula P = M x wwhere M=torque (Nm) and w=angular speed (rad/s). It should be understood that PM motor power increases to a large extent with rpm and thus angular velocity. Thanks to their high weight/power ratio and high speed range, permanent magnet motors PM motors have the advantage that even a very small motor can offer very high mechanical power in the higher speed registers. Since the size of an electric machine at a given power level can be reduced through increased rotation speed, the PM machine has the advantage that, if necessary, they can offer very high power by rotating synchronously in work areas in very high adjustable speed registers, for example 0 - 10,000 revolutions per minute or more.

Thanks to the fact that the system according to the present invention uses electronic direct control of a combination of PM motor and pump, the inventive system can offer very fast response times (response times), which has been a problem with the known technology.

Fig. 4 shows in more detail an example of a motor drive unit generally denoted by 52' for a permanent magnet motor 15' of AC type, a so-called PMAC engine according to the invention. Contrary to inductive alternating current motors, it should be pointed out that in (AC motors) must P:\Stockholm\mfh\Skrivbord\Skrivbord 171207\New Folder\Brokk\P41801041SEOOP140373S EOO\P140373S EO1\220519 besk o patent claims divided application.docxpermanently magnetized motors (PM motors ) is controlled and controlled with a motor drive unit 52' for motor control.

Said motor drive unit 52' includes a motor control unit 53' which is connected to the control unit 50' for transmitting a variable control signal 51' to the PMAC motor 15' and driving the pump 13' with desired operating parameters. PMAC motors have AC induction motor simplicity and reliability while offering higher efficiency, synchronous operation and the ability to use a smaller frame size and thus can deliver a given torque with a more compact and lightweight machine. When each consumer's L1, L2 flow demand is down to 0, the pump and motor are completely at a standstill, whereby all forms of idle losses are eliminated.

In the present embodiment, pulse width modulation (PWM) is used to control the PMAC motor's torque and angular velocity (speed). Since according to the present invention it is about electronic control data 31', 51', in contrast to known demolition robots that use an analog hydraulic pressure to control the pump, it is conceivable that the control unit 50 can include a computer-readable storage medium 60 denoted DB in fig.3 to store control data , error codes or other useful data to carry out analysis of control data, for example during service.

The control device 40 comprises a drive unit 54' for the PMAC motor whose function, since it is well known in itself, will not be described in more detail in the following. Broadly, the drive unit 54' includes a three-phase inverter for converting an incoming DC voltage to a three-phase AC voltage. The DC voltage can for example be obtained from a DC bus which in turn, via a rectifier not shown in the figure, obtains its power from a 400 V AC network via the cable 2 or alternatively directly to the demolition robot 1. The motor control unit 53' further includes a current sensor 55' which measures said DC bus from a battery pack on board the respective phase currents to the PMAC motor 15' as well as a speed/position sensor 56' which measures the position and speed of the output drive shaft of the PMAC motor. This data can be addressed back to the control unit 50' via the I/O interface that the control unit is equipped with. Thanks to the invention with a speed-controlled hydraulic pump, an end demolition robot is obtained with a compact, inexpensive, energy-efficient system. In an embodiment with speed control of a PM motor and thus pump capacity, pump power can vary with flow and pressure of the hydraulic fluid within a large range and where every flow need of the consumer is met with a significantly reduced risk of punctures occurring in the system. By using PWM control, The speed of the PMAC motor is controlled and changed a thousand times per second (ie in the kHz range) and thus with very fast response times and basically stepless. This means that the problems of previous demolition robots' long response times (response times) of the hydraulic systems can be significantly improved.

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Claims (1)

1. 1. Demolition robot (1), comprising; an incoming supply line (P) for hydraulic flow, an outgoing return line (T) for hydraulic flow, and an outgoing load sensing line (LS) for sensing hydraulic load of a hydraulic operative function (L1, L2), a sensing device (30) for sensing a hydraulic pressure in the load sensing line (LS), a control device (40) comprising a pump (13') with fixed displacement for generating a hydraulic flow to said hydraulically active function (L1, L2), a speed-adjustable drive motor (15') which is connected to said pump (13'), a motor drive unit (52') which for speed control of the drive motor (15'), includes a control unit (50') which is arranged to receive an electronic measurement signal (31') from the sensor device (30) and via control data (51 ') control the rotational speed of the drive motor (15') included in the control device (40) to cause the pump (13') to produce a predetermined pressure on the load sensing line (LS), characterized in that the drive motor (15') comprises a permanently magnetized three-phase AC motor (PMAC motor), and that the motor drive unit (52) further comprises a motor control unit (53') which is connected to the control unit (50') for transmitting a variable control signal (51') to the drive motor (15') and driving the pump ( 13') with desired operating parameters, that the motor control unit (53') includes a current sensor (55') which measures a respective phase current to the drive motor (15') and a speed/position sensor (56') which measures the position and speed of the drive motor (15') output the drive shaft, an I/O interface with which the data from said current sensor (55') and speed/position sensor (56') are addressed back to the control unit (50'), whereby the drive motor's (15') torque and angular velocity (speed) are controlled by means of pulse width modulation (PvvM) . Demolition robot according to claim 1, wherein the drive motor (15') is of the type which exhibits one of the following speed ranges 0-2000 revolutions per minute, 0-3000 revolutions per minute or more than 3000 revolutions per minute. Demolition robot according to one of claims 1 - 2, wherein the control unit (50') comprises a PLC or a microprocessor CPU with a computer program which P:\Stockho|m\mfh\Desktop\Desktop 171207\New Fo|der\Brokk\P41801041SEOO131403738 EOO\ P140373S EO1\220519 besk o patent claim divided application.docx - based on a measuring signal (31') input to the control unit (50') for pressure from the sensing device (30), - a set position of a control lever (8) included in the demolition robot (1) for steering and control of the hydraulic first and second consumers (L1, L2) included in the demolition robot, and - an outgoing control signal (51') from the control unit (50') to a motor drive unit (52') arranged for the drive motor (15'), can control and regulate the speed of the drive motor (15') so that the pump (13') can deliver the effect in the form of flow and pressure of the hydraulic fluid that the first and/or the second consumer (L1, L2) requests. Demolition device according to one of claims 1 - 3, wherein the sensor device (30) includes a pressure sensor (PT) and that the signal from said pressure sensor to the control unit (50') is an electronic measurement signal (31') for pressure. Demolition robot according to any of claims 1 - 4, comprising a computer-readable storage medium (60') arranged for the control unit (50'). Demolition robot according to claim 5, wherein the storage medium (60') can be used to store control data, error codes or other useful motor control data from the control unit (50'). Method for supplying hydraulic power to a hydraulically driven tool (L1) which is exchangeably supported at a free end of an arm (3) included in a demolition robot (1) and to the hydraulic cylinder (L2) with which the arm can be maneuvered, which method includes the following operations step; - via a supply line (P) to feed a flow of pressurized hydraulic fluid to the tool (L1) from a hydraulic drive device (13', 15') to a hydraulically coordinated function included in the tool (L1), - to return hydraulic fluid via a return line (T) to the hydraulic drive device, and - to return via a load sensing line (LS) a signal pressure for controlling the hydraulic drive device (13', 15'), characterized by, - that a permanently magnetized three-phase AC motor (PMAC motor) is used as drive motor (15'), - that a pressure in the load sensing line (LS) is measured and that the pressure is converted into an electronic measurement signal (31'), P:\Stockholm\mfh\Skrivbord\Skrivbord 171207\New Folder\Brokk\P41801041SEOO131403738 EOO\P140373S EO1\220519 besk o patent claim dept. application.docx - that the electronic measurement signal (31') is used to cause a pump (13') with fixed displacement to produce a predetermined pressure on the load sensing line (LS) based on the measured pressure, - that a respective phase current to the drive motor ( 15') is measured by means of a current sensor (55'), that the position and speed of the output drive shaft of the drive motor (15') is measured by means of a speed/position sensor (56'), - that data from said current sensor (55') and speed/position sensor (56 ') address back to the control unit (50') via an I/O interface and - that the drive motor's (15') torque and angular speed (speed) are controlled by means of pulse width modulation (PWM). 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